The present invention relates generally to apparatus for charging raw batch material into a glass melting furnace and, more particularly, to so-called blanket batch chargers. U.S. Pat. No. 4,483,206, as well as U.S. Pat. Nos. 3,780,889 and 4,197,109 to Frazier et al., all commonly owned with the present invention, disclose so-called "large" blanket chargers. Such large blanket chargers are used in conjunction with glass furnaces of the type having firing burners mounted along the sides of the furnace wherein the batch charger is positioned adjacent an end of the furnace referred to as the "dog house" 3 A continuous furnace used for the manufacture of glass of this type comprises a large rectangular tank in which the molten bath of glass is contained. The raw batch material is continuously introduced into the rear of the furnace by the batch charging apparatus. Such large furnaces are capable of delivering from about 10 tons per day to about 10,000 tons per day of glass. The so-called dog house feeding area for these large furnaces extends across a substantial part of the full width of the furnace which can be on the order of from 20 to 30 feet. The so-called large blanket chargers may be employed in side-by-side configuration to extend along this full expanse. The charging bay or dog house of an end feed, side fired, large furnace structure typically includes a suspended wall set inwardly from a lower rear wall of the charging bay, leaving an open or semi-open trough therebetween defining the so-called dog house across a substantial part of the full width of the furnace. The dog house provides a downwardly extending, open area above the area of the molten glass into which the mixture of raw batch is charged. These large machines are mechanically driven as fully described in the above-referenced application and issued patents. The raw batch material initially floats on the molten glass and melts as it moves forward into the furnace proper. Such conventional batch chargers have a charger plate that downwardly extends into the dog house area and reciprocates in a direction along the long axis of the furnace. The charger plate is positioned beneath a hopper chute such that as the charger plate moves forward from a retracted limit of travel, raw batch material from the hopper chute is deposited in a layer on the charger plate. Simultaneously, the nose or forward edge of the charger plate pushes a previously deposited layer of the floating batch under the suspended wall at the end of the dog house into the melting zone of the furnace. As the charger plate moves rearwardly, the layer of batch material then residing on the charger plate is obstructed by a sand seal device at the rear of the hopper from being carried rearwardly and is moved off of the charger plate to fall over the nose thereof into the open area of the furnace from which the previous charge has just been cleared. This reciprocating cycle is continuously repeated to maintain a substantially constant level or blanket of charge and, hence, level of molten glass in the furnace as the melt is removed at the fore hearth region.
Due to the mechanically driven nature of the large blanket chargers, the length of the feeding stroke determined by the length of travel of the charger plate is not easily adjustable and requires some machine downtime in order to make changes thereto. In addition, the charger plates of these larger blanket batch chargers only travel in the sheltered area of the dog house wherein the upper surfaces of the charger plate are not exposed to direct flame impingement by the burners.
The present invention, on the other hand, relates to a blanket charger for use in a smaller, end fired furnace having its charging openings located at the sides thereof. For comparison purposes, these smaller, end fired furnaces generally have from about one ton per day upwards to about 500 tons per day of glass manufacturing capability. In such end fired furnaces, the flame from the burners generally traverses the area of the charging openings. This flame pattern makes it difficult to utilize a blanket type charger since the charger plate thereof must extend partially into the flame front and localized melting of the charger plate might result. Commonly used prior art reciprocating pusher type chargers employed in side fed, end fired furnaces are not wholly effective because they are not capable of metering or controlling the glass batch. These pusher type chargers can not feed a wet batch and, therefore, dusting is a problem common to these prior machines. In addition, the stroke speed and stroke length of prior chargers cannot be easily adjusted so as to make immediate charging changes in the furnace possible.
The present invention solves the problems heretofore encountered in end fired, side fed glass furnaces by providing a small blanket charger capable of charging a wet batch material to prevent dusting problems and having the capability of adjusting the stroke length and speed without shutting down the machine. The present invention provides a blanket charger which meters and controls the raw batch material to a degree unknown by the prior art reciprocating pusher type chargers commonly employed in side charged, end fired glass furnaces. The present invention provides a blanket charger which dispenses with the complicated mechanical linkages and shafts commonly employed in chargers of the prior art. The present invention further provides a blanket charger which is substantially self-contained and compact and has fewer moving parts than prior chargers, thus, requiring far less maintenance than conventional batch chargers.